The present invention relates generally to the field of highway snow and ice melting procedures, and more particularly, is directed to a system suitable to extend the melting capability and efficiency of highway ice control salt.
In northern latitudes, it is common practice to provide increased highway safety during the winter months by applying common salt in granular or pellet sizes directly upon accumulations of ice and snow in the road surface to thereby effect early melting and consequential highway clearing, even at temperatures below 32.degree. F. Large, open trucks equipped with salt spreading apparatus and capable of being filled with usual front end loaders are normally employed for this purpose. Additionally, it has also been common practice to apply a gritty material, such as sand or cinders, upon accumulations of highway ice in order to further render highway systems safer for travel by automobile during the winter months.
In the case of the application of salt particles, it has been found that the usual sodium chloride salt application works well enough to melt rather quickly the accumulations of ice and snow from most winter storms when ambient temperatures are either above freezing or slightly below freezing. However, as the weather conditions become worse and temperatures decline, the clearing of accumulations of ice and snow from highway surfaces becomes increasingly more difficult due to the slower melting that can be expected, even after repeated applications of dry salt. Additionally, as the temperature drops, the salt particles have a tendency to bounce upon the cold highway surface as they are delivered upon the road surface by the spreading equipment and thus do not remain in the desired pattern directly within the cartway wherein the melting of the ice is most desirable and necessary.
In order to improve the snow and ice melting capabilities of highway salt at lower temperatures, prior workers in the field have found that the addition of dry calcium chloride pellets to the dry sodium chloride salt has increased snow and ice melting capabilities of the salt, especially at temperatures below 25.degree. F. As the ambient temperatures have declined, increased amounts of dry calcium chloride pellets have been added in an effort to provide improved snow and ice melting at such lower temperatures. While the addition of calcium chloride pellets did provide increased snow and ice melting capability of the highway salt, the lower temperatures resulted in slower melting. Additionally, the problem of pellet "bounce" remained and a considerable portion of the applied material did not remain in the location of application and accordingly, was not available to promote melting where most needed.
Prior workers in the art have developed wetted salt systems suitable to apply a brine solution of liquid calcium chloride to sodium chloride salt granules prior to application upon a highway surface for snow and ice melting during periods of below freezing temperatures.
Such prior systems have included liquid storage tanks of suitable construction and capacity which were provided with necessary fittings to both store a quantity of liquid calcium chloride solution without corrosion and to feed the brine solution to delivery equipment for subsequent automatically controlled spraying upon loads of highway ice melting salt.
The prior systems have incorporated a hydraulic pump and a brine pump which were designed and provided to receive brine from the storage tank and to deliver the brine solution to a wetting arm for direct application upon each load of highway salt granules as the salt was delivered to a conventional spreader truck by a suitable truck loading apparatus, such as a front end loader.
The wetting arm was pivotal in nature to facilitate application of the brine solution during the truck loading operation and the pivotal operation of the arm was functioned and controlled by the hydraulic unit. In the usual application, the bucket of a front end loader or the storage compartment of the truck was moved to the wetting arm which was then lowered and the brine solution was applied directly upon the salt through spray pattern nozzles. After each application of the brine solution, the wetting arm was pivotally raised or otherwise moved to facilitate free movement of the loading equipment and the truck. The length of the spray cycle was usually controlled by one or more timers as part of the control circuit. As is usual with most available timers, the timed period of operation had to be set directly within the timer itself. Such wettings had to be made by skilled personnel using the necessary tools to effect timer adjustment. Problems have occurred wherein changes in weather conditions or in load conditions would have indicated that a different timer setting could be more advantageously employed to adjust the quantity of liquid calcium chloride being applied. However, with existing equipment, there was no easy or timely method for making any such adjustment.